1. Field of the Invention
The present invention relates to a passenger protection system such as a vehicle air bag system, and more particularly to a collision-determining circuit of the passenger protection system for determining whether or not a collision has occurred, and for preventing erroneous system deployment.
2. Discussion of the Related Art
Conventional collision determination devices are of the type shown, for example, in U.S. Pat. No. 5,038,134. As shown in FIG. 21, such a collision determination device generates, prior to determining whether or not a collision has occurred, a pseudo signal 2 from an acceleration sensor based on a control signal 1 to determine whether an air bag system is malfunctioning based on the pseudo signal 2.
However, as shown in FIG. 21, the polarity of the pseudo signal 2 is the same as that of an acceleration signal 3 generated from the acceleration sensor when the vehicle is involved in a collision.
Therefore, the airbag system may be activated erroneously as the pseudo signal 2 is generated when the pseudo signal 2 is erroneously output even though no acceleration signal is generated.
Further, when a plurality of acceleration sensors are implemented in the collision detection system, the above-discussed limitation still remains, as the control signal 1 is used in common in the respective acceleration sensors. Accordingly, the air bag system may be erroneously activated in the same manner as described above.